This invention relates to aryl ether sulfones, and to their use as lubricating fluids and as lubricity-enhancing additives.
It is generally known that aryl ether sulfones are useful as lubricating fluids. For example, U.S. Pat. No. 2,998,453 discloses certain aryl ether sulfones which are taught to be useful as lubricants. However, such aryl ether sulfones may not be thermally stable at extremely high temperatures, such as temperatures above about 300.degree. C., and may also have lubricating properties which are poorer than desired.
One type of lubricating fluids known to be useful for high temperature applications is the perfluoroalkyl ethers. However, such compounds are often insoluble or otherwise incompatible with most hydrocarbon, ester, and aromatic-based lubricating fluids, and have higher densities than are desired for such applications. In addition, such compounds give off hydrogen fluoride gas upon decomposition.
Another type of lubricating fluids known to be useful for high temperature applications are polyaryl ether fluids. However, such fluids have lubricating properties which are less than are desired for many applications.